In German Published Patent Application No. 199 06 287, the exhaust gas aftertreatment system includes a particulate filter, which is used particularly for directly injecting internal combustion engines. In that case, the loading of the particulate filter is recorded as the state variable, and, when certain values are exceeded, a special operating state is initiated in which the particulate filter is regenerated by suitable measures.
In this context, the regeneration is carried out only as a function of the loading of the particulate filter, i.e. of the mass of soot present in the particulate filter, which is ascertained by suitable methods. Each regeneration of the particulate filter requires additional fuel, which, for example, is metered in a postinjection operation or which is appropriately metered to elevate the exhaust gas temperature.